[FFmpeg-devel] Patch libavformat/aviobuf.c fixes data loss on named pipe reads

[Michael Niedermayer]

On Fri, May 12, 2017 at 06:31:19PM +0000, Rob Meyers wrote:
> Submitting a patch to fix a bug in ffmpeg found when reading data from a
> named pipe. In our test, a pipe sending twelve bytes in two 6 byte messages
> results in the first 10 bytes being lost. We found the problem was
> introduced with this commit (2ca48e466675a8a3630061cd2c15325eab8eda97) on
> June 30, 2013. In this code, the "dst" pointer is always set to s->buffer,
> and earlier message bytes are overwritten by later ones when assembling a
> packet from multiple small reads.
> 
> 
> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> index 0a7c39eacd..4e04cb79e0 100644
> --- a/libavformat/aviobuf.c
> +++ b/libavformat/aviobuf.c
> @@ -519,9 +519,7 @@ void avio_write_marker(AVIOContext *s, int64_t time,
> enum AVIODataMarkerType typ
> 
>  static void fill_buffer(AVIOContext *s)
>  {
> -    int max_buffer_size = s->max_packet_size ?
> -                          s->max_packet_size : IO_BUFFER_SIZE;
> -    uint8_t *dst        = s->buf_end - s->buffer + max_buffer_size <
> s->buffer_size ?
> +    uint8_t *dst        = !s->max_packet_size && s->buf_end - s->buffer <
> s->buffer_size ?

Patch is corrupted by linebreaks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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